fixes quickstart documentation to head over installation/how to run app for each platform

doc/sources/guide/installation-macosx.rst

@@ -30,6 +30,8 @@ Start any Kivy Application
 You can run any Kivy application by simply dragging the application's main file
 onto the Kivy.app icon. Just try with any python file in the examples folder.
 
+.. _macosx-run-app:
+
 Start from Command Line
 -----------------------
 

doc/sources/guide/installation-ubuntu.rst

@@ -15,6 +15,12 @@ If you already installed kivy before, you can upgrade it with::
 
     $ easy_install -U kivy
 
+
+.. _linux-run-app:
+
+Start from Command Line
+-----------------------
+
 You can know run any example from the examples directory of kivy::
 
     $ cd <path to kivy directory>/examples/demo

doc/sources/guide/installation-window.rst

@@ -10,6 +10,8 @@ to install anything in "system" wide. Just unzip & run:
        use it for launching any kivy application
 
 
+.. _windows-run-app:
+
 Start any Kivy's application
 ----------------------------
 

doc/sources/guide/quickstart.rst

@@ -25,9 +25,30 @@ The base code for creating an application looks like this:
 
     MyApp().run()
 
-Save it as `myapp.py` and run it with your Python interpreter ::
+Save it as `myapp.py`.
 
-    $ python myapp.py
+Now, to run your application, depending of your platform, you can :
+
+    Linux
+        Follow the instructions for :ref:`running Kivy application on Linux <linux-run-app>`::
+
+            $ python myapp.py
+
+    Windows
+        Follow the instructions for :ref:`running Kivy application on Windows <windows-run-app>`::
+            
+            $ python myapp.py
+            # or
+            C:\appdir>kivy.bat myapp.py
+
+    MacOSX
+        Follow the instructions for :ref:`running Kivy application on MacOSX <macosx-run-app>`::
+
+            $ kivy myapp.py
+
+    Android
+        You application need some complementary files to be able to run on Android.
+        See :doc:`android` for more informations.
 
 A window should open, showing a sole button (with the label 'Hello World') that
 covers the entire window's area. That's all there is to it.